Risk Discrimination of Eye Contact and Directness of Approach in Black Iguanas (Ctenosaura similis )

We examined the ability of basking black iguanas ( Ctenosaura similis ) to discriminate risk from a person walking directly toward them versus one walking tangentially by them when the person looked either directly at them or away from them. All iguanas were tested near the Organization for Tropical Studies Palo Verde, Costa Rica field station or the refuge hacienda, where they were habituated to the presence of humans. The animals responded most quickly to a direct approach with a direct gaze, followed by a direct approach with an averted gaze and a tangential approach with a direct gaze, and least quickly to a tangential approach with an averted gaze. Behavioral responses were not related to body size but were intercorrelated. These results demonstrate that iguanas can use both body orientation and gaze direction to assess the threat of an approaching predator.